Seeing how the German northern coast lay under the blockade by the Danish navy, Bauer quickly developed a plan to build a new kind of ship to help break the blockade.

To accomplish that, Bauer began studying hydraulics and ship construction. But before his studies could bear any fruit the troops of the German Confederation decided to withdraw and surrender Schleswig-Holstein to the Danish. Bauer, however, was determined to realize his plan at any cost and left service in the German army to join the forces of Schleswig-Holstein.

It proved very hard for Bauer, who had a low military rank, to bring his plan through the various instances of the military administration and to gain fundings to build his craft. He finally succeeded with the help of Werner von Siemens and others and was granted a small sum of money to built a model of his submarine.

The Brandtaucher ("incendiary diver") submarine

Incendiary ships were a well known concept in blockade-breaking. A ship was loaded with explosives and set free to drift into the enemy fleet, exploding at contact. The incendiary diver was planned to work on a similar principle: It would dive under an enemy vessel, fix an electrically triggered mine to its hull and escape, igniting the mine from a safe distance. The more or less same technique was employed by all military submarine designs of that time, like Julius Kröhl’s Explorer, the U.S.S. Alligator by Brutus de Villeroi and the famous Hunley, which became the first submarine to sink an enemy vessel.

After the model of the submarine, built by Bauer himself, proved to be working, he was granted enough money to build a full scale submarine. But the military authorities still were largely against Bauer’s plan and forced Bauer to change his designs in order to reduce costs.

The finished Brandtaucher, built by August Howaldt of the later Howaldtswerke was 28 feet long, weighing about 70,000 pounds. As at that time no suitable mechanical power system was available the submarine was powered by two sailors turning a big tread wheel with their hands and feet. The third crew member, the captain, was positioned at the stern of the submarine. His job was to operate the rudders and other controls. Having arrived under the target ship the captain would reach out through a gutta percha (rubber) glove fixed to an opening of the hull, grab the mine located within reach on the hull of the submarine and fix it on the target.

Had the Brandtaucher been built according to Bauer’s original designs, it would have achieved submersion by filling several tanks with sea water. But in the changed version the vessel itself was to be partly flooded with water, thus rendering the submarine dangerously unstable. Also the thickness of the hull and the dimensions of the pumps had to be greatly reduced.

First trials of the submarine took place in December 1850. Although Bauer wanted to make several improvements of the submarine, the military ordered a public show on the 1st of February, 1851.

This public demonstration almost ended in a disaster. After reaching a depth of 30 ft the craft began to lay down by the stern. As the submarine sank down the thin walls could not take the water pressure any more and started to crack. The water pressure proved too much for the weak pumps and the propeller wheel was damaged when the vessel began to keel over. The submarine slowly sank to the ground of the Kiel harbour.
For six hours Bauer and his sailors had to wait inside the sunken craft, until enough water had seeped in. This increased the air pressure inside the submarine and finally allowed the men to open the blocked hatchway. As the submarine stayed buried on the ground of the sea, its crew came to the surface unharmed.

The Seeteufel ("sea devil") submarine

After the sinking of the Brandtaucher Bauer instantly began to make plans for an improved, larger submarine. But the government of Schleswig-Holstein refused to support Bauer after their bad experience with Bauer’s first submarine.

So Bauer left Schleswig-Holstein. In the following years he tried to obtain support for his invention in several countries, like the Austria-Hungary, the British Empire or France. Finally, in 1855 Bauer made a contract with the grand prince of St. Petersburg (Russia).
During that year Bauer built his second submarine, the Seeteufel (sea devil) in St. Petersburg.
Of this submarine much less is known than of the Brandtaucher. It is said to have been twice as long as its predecessor, its iron walls 1/2' thick with 21 windows in them. It had three big cylinders to hold water as immersion weight and was designed for a crew of 12.

Having learned from his first boat’s disaster Bauer provided the sea devil with a newly invented rescue device: the diver’s chamber. Through this chamber, which worked like an airlock, divers could leave and enter the submerged vessel.

The sea devil proved to be a very good design. It made 133 successful diving runs within four months. But during the 134th dive the submarine got stuck in the sand of the ground of the sea. By emptying the water cylinders with the pumps the crew managed to raise the submarine high enough so that the hatchway was above the waterline. The whole crew (including Bauer) was saved but the submarine sank back to the bottom of the sea.

Legacy

After the end of the sea devil Bauer soon left Russia. When he realized he wouldn’t find support for another submarine he took to other projects. In 1863 Bauer managed to raise a sunken ship by means of inflatable balloons made of canvas. But all his more ambitious plans failed because of a complete lack of fundings.
Disappointed by this Bauer died in 1875 in Munich.

It would be wrong to claim that the German submarine fleet of the world wars was directly descended from Wilhelm Bauer’s prototypes. The modern submarine began its history with the inventions of Simon Lake and John Philip Holland. The submarine pioneers of the 19th century however - de Villeroi, Monturiol, Hunley and others - were well aware of Bauer’s invention and derived many ideas and inspirations from it. And without these men, we wouldn’t have the technically advanced submarines we have today.